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<pre><span class="sourceLineNo">001</span>/*<a name="line.1"></a>
<span class="sourceLineNo">002</span> * Licensed to the Apache Software Foundation (ASF) under one or more<a name="line.2"></a>
<span class="sourceLineNo">003</span> * contributor license agreements.  See the NOTICE file distributed with<a name="line.3"></a>
<span class="sourceLineNo">004</span> * this work for additional information regarding copyright ownership.<a name="line.4"></a>
<span class="sourceLineNo">005</span> * The ASF licenses this file to You under the Apache License, Version 2.0<a name="line.5"></a>
<span class="sourceLineNo">006</span> * (the "License"); you may not use this file except in compliance with<a name="line.6"></a>
<span class="sourceLineNo">007</span> * the License.  You may obtain a copy of the License at<a name="line.7"></a>
<span class="sourceLineNo">008</span> *<a name="line.8"></a>
<span class="sourceLineNo">009</span> *      http://www.apache.org/licenses/LICENSE-2.0<a name="line.9"></a>
<span class="sourceLineNo">010</span> *<a name="line.10"></a>
<span class="sourceLineNo">011</span> * Unless required by applicable law or agreed to in writing, software<a name="line.11"></a>
<span class="sourceLineNo">012</span> * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.12"></a>
<span class="sourceLineNo">013</span> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.13"></a>
<span class="sourceLineNo">014</span> * See the License for the specific language governing permissions and<a name="line.14"></a>
<span class="sourceLineNo">015</span> * limitations under the License.<a name="line.15"></a>
<span class="sourceLineNo">016</span> */<a name="line.16"></a>
<span class="sourceLineNo">017</span><a name="line.17"></a>
<span class="sourceLineNo">018</span><a name="line.18"></a>
<span class="sourceLineNo">019</span>package org.apache.commons.net.nntp;<a name="line.19"></a>
<span class="sourceLineNo">020</span><a name="line.20"></a>
<span class="sourceLineNo">021</span>/**<a name="line.21"></a>
<span class="sourceLineNo">022</span> * This is an implementation of a message threading algorithm, as originally devised by Zamie Zawinski.<a name="line.22"></a>
<span class="sourceLineNo">023</span> * See &lt;a href="http://www.jwz.org/doc/threading.html"&gt;http://www.jwz.org/doc/threading.html&lt;/a&gt; for details.<a name="line.23"></a>
<span class="sourceLineNo">024</span> * For his Java implementation, see &lt;a href="http://lxr.mozilla.org/mozilla/source/grendel/sources/grendel/view/Threader.java"&gt;http://lxr.mozilla.org/mozilla/source/grendel/sources/grendel/view/Threader.java&lt;/a&gt;<a name="line.24"></a>
<span class="sourceLineNo">025</span> *<a name="line.25"></a>
<span class="sourceLineNo">026</span> * @author rwinston &lt;rwinston@checkfree.com&gt;<a name="line.26"></a>
<span class="sourceLineNo">027</span> *<a name="line.27"></a>
<span class="sourceLineNo">028</span> */<a name="line.28"></a>
<span class="sourceLineNo">029</span><a name="line.29"></a>
<span class="sourceLineNo">030</span>import java.util.HashMap;<a name="line.30"></a>
<span class="sourceLineNo">031</span>import java.util.Iterator;<a name="line.31"></a>
<span class="sourceLineNo">032</span>import java.util.List;<a name="line.32"></a>
<span class="sourceLineNo">033</span><a name="line.33"></a>
<span class="sourceLineNo">034</span>public class Threader {<a name="line.34"></a>
<span class="sourceLineNo">035</span>    private ThreadContainer root;<a name="line.35"></a>
<span class="sourceLineNo">036</span>    private HashMap&lt;String,ThreadContainer&gt; idTable;<a name="line.36"></a>
<span class="sourceLineNo">037</span>    private int bogusIdCount = 0;<a name="line.37"></a>
<span class="sourceLineNo">038</span><a name="line.38"></a>
<span class="sourceLineNo">039</span>    /**<a name="line.39"></a>
<span class="sourceLineNo">040</span>     * The client passes in a list of Threadable objects, and<a name="line.40"></a>
<span class="sourceLineNo">041</span>     * the Threader constructs a connected 'graph' of messages<a name="line.41"></a>
<span class="sourceLineNo">042</span>     * @param messages list of messages to thread<a name="line.42"></a>
<span class="sourceLineNo">043</span>     * @return null if messages == null or root.child == null<a name="line.43"></a>
<span class="sourceLineNo">044</span>     * @since 2.2<a name="line.44"></a>
<span class="sourceLineNo">045</span>     */<a name="line.45"></a>
<span class="sourceLineNo">046</span>    public Threadable thread(List&lt;? extends Threadable&gt; messages) {<a name="line.46"></a>
<span class="sourceLineNo">047</span>        return thread((Iterable&lt;? extends Threadable&gt;)messages);<a name="line.47"></a>
<span class="sourceLineNo">048</span>    }<a name="line.48"></a>
<span class="sourceLineNo">049</span><a name="line.49"></a>
<span class="sourceLineNo">050</span>    /**<a name="line.50"></a>
<span class="sourceLineNo">051</span>     * The client passes in a list of Iterable objects, and<a name="line.51"></a>
<span class="sourceLineNo">052</span>     * the Threader constructs a connected 'graph' of messages<a name="line.52"></a>
<span class="sourceLineNo">053</span>     * @param messages iterable of messages to thread<a name="line.53"></a>
<span class="sourceLineNo">054</span>     * @return null if messages == null or root.child == null<a name="line.54"></a>
<span class="sourceLineNo">055</span>     * @since 3.0<a name="line.55"></a>
<span class="sourceLineNo">056</span>     */<a name="line.56"></a>
<span class="sourceLineNo">057</span>    public Threadable thread(Iterable&lt;? extends Threadable&gt; messages) {<a name="line.57"></a>
<span class="sourceLineNo">058</span>        if (messages == null) {<a name="line.58"></a>
<span class="sourceLineNo">059</span>            return null;<a name="line.59"></a>
<span class="sourceLineNo">060</span>        }<a name="line.60"></a>
<span class="sourceLineNo">061</span><a name="line.61"></a>
<span class="sourceLineNo">062</span>        idTable = new HashMap&lt;String,ThreadContainer&gt;();<a name="line.62"></a>
<span class="sourceLineNo">063</span><a name="line.63"></a>
<span class="sourceLineNo">064</span>        // walk through each Threadable element<a name="line.64"></a>
<span class="sourceLineNo">065</span>        for (Threadable t : messages) {<a name="line.65"></a>
<span class="sourceLineNo">066</span>            if (!t.isDummy()) {<a name="line.66"></a>
<span class="sourceLineNo">067</span>                buildContainer(t);<a name="line.67"></a>
<span class="sourceLineNo">068</span>            }<a name="line.68"></a>
<span class="sourceLineNo">069</span>        }<a name="line.69"></a>
<span class="sourceLineNo">070</span><a name="line.70"></a>
<span class="sourceLineNo">071</span>        root = findRootSet();<a name="line.71"></a>
<span class="sourceLineNo">072</span>        idTable.clear();<a name="line.72"></a>
<span class="sourceLineNo">073</span>        idTable = null;<a name="line.73"></a>
<span class="sourceLineNo">074</span><a name="line.74"></a>
<span class="sourceLineNo">075</span>        pruneEmptyContainers(root);<a name="line.75"></a>
<span class="sourceLineNo">076</span><a name="line.76"></a>
<span class="sourceLineNo">077</span>        root.reverseChildren();<a name="line.77"></a>
<span class="sourceLineNo">078</span>        gatherSubjects();<a name="line.78"></a>
<span class="sourceLineNo">079</span><a name="line.79"></a>
<span class="sourceLineNo">080</span>        if (root.next != null) {<a name="line.80"></a>
<span class="sourceLineNo">081</span>            throw new RuntimeException("root node has a next:" + root);<a name="line.81"></a>
<span class="sourceLineNo">082</span>        }<a name="line.82"></a>
<span class="sourceLineNo">083</span><a name="line.83"></a>
<span class="sourceLineNo">084</span>        for (ThreadContainer r = root.child; r != null; r = r.next) {<a name="line.84"></a>
<span class="sourceLineNo">085</span>            if (r.threadable == null) {<a name="line.85"></a>
<span class="sourceLineNo">086</span>                r.threadable = r.child.threadable.makeDummy();<a name="line.86"></a>
<span class="sourceLineNo">087</span>            }<a name="line.87"></a>
<span class="sourceLineNo">088</span>        }<a name="line.88"></a>
<span class="sourceLineNo">089</span><a name="line.89"></a>
<span class="sourceLineNo">090</span>        Threadable result = (root.child == null ? null : root.child.threadable);<a name="line.90"></a>
<span class="sourceLineNo">091</span>        root.flush();<a name="line.91"></a>
<span class="sourceLineNo">092</span>        root = null;<a name="line.92"></a>
<span class="sourceLineNo">093</span><a name="line.93"></a>
<span class="sourceLineNo">094</span>        return result;<a name="line.94"></a>
<span class="sourceLineNo">095</span>    }<a name="line.95"></a>
<span class="sourceLineNo">096</span><a name="line.96"></a>
<span class="sourceLineNo">097</span>    /**<a name="line.97"></a>
<span class="sourceLineNo">098</span>     *<a name="line.98"></a>
<span class="sourceLineNo">099</span>     * @param threadable<a name="line.99"></a>
<span class="sourceLineNo">100</span>     */<a name="line.100"></a>
<span class="sourceLineNo">101</span>    private void buildContainer(Threadable threadable) {<a name="line.101"></a>
<span class="sourceLineNo">102</span>        String id = threadable.messageThreadId();<a name="line.102"></a>
<span class="sourceLineNo">103</span>        ThreadContainer container = idTable.get(id);<a name="line.103"></a>
<span class="sourceLineNo">104</span><a name="line.104"></a>
<span class="sourceLineNo">105</span>        // A ThreadContainer exists for this id already. This should be a forward reference, but may<a name="line.105"></a>
<span class="sourceLineNo">106</span>        // be a duplicate id, in which case we will need to generate a bogus placeholder id<a name="line.106"></a>
<span class="sourceLineNo">107</span>        if (container != null) {<a name="line.107"></a>
<span class="sourceLineNo">108</span>            if (container.threadable != null) { // oops! duplicate ids...<a name="line.108"></a>
<span class="sourceLineNo">109</span>                id = "&lt;Bogus-id:" + (bogusIdCount++) + "&gt;";<a name="line.109"></a>
<span class="sourceLineNo">110</span>                container = null;<a name="line.110"></a>
<span class="sourceLineNo">111</span>            } else {<a name="line.111"></a>
<span class="sourceLineNo">112</span>                // The container just contained a forward reference to this message, so let's<a name="line.112"></a>
<span class="sourceLineNo">113</span>                // fill in the threadable field of the container with this message<a name="line.113"></a>
<span class="sourceLineNo">114</span>                container.threadable = threadable;<a name="line.114"></a>
<span class="sourceLineNo">115</span>            }<a name="line.115"></a>
<span class="sourceLineNo">116</span>        }<a name="line.116"></a>
<span class="sourceLineNo">117</span><a name="line.117"></a>
<span class="sourceLineNo">118</span>        // No container exists for that message Id. Create one and insert it into the hash table.<a name="line.118"></a>
<span class="sourceLineNo">119</span>        if (container == null) {<a name="line.119"></a>
<span class="sourceLineNo">120</span>            container = new ThreadContainer();<a name="line.120"></a>
<span class="sourceLineNo">121</span>            container.threadable = threadable;<a name="line.121"></a>
<span class="sourceLineNo">122</span>            idTable.put(id, container);<a name="line.122"></a>
<span class="sourceLineNo">123</span>        }<a name="line.123"></a>
<span class="sourceLineNo">124</span><a name="line.124"></a>
<span class="sourceLineNo">125</span>        // Iterate through all of the references and create ThreadContainers for any references that<a name="line.125"></a>
<span class="sourceLineNo">126</span>        // don't have them.<a name="line.126"></a>
<span class="sourceLineNo">127</span>        ThreadContainer parentRef = null;<a name="line.127"></a>
<span class="sourceLineNo">128</span>        {<a name="line.128"></a>
<span class="sourceLineNo">129</span>            String[] references = threadable.messageThreadReferences();<a name="line.129"></a>
<span class="sourceLineNo">130</span>            for (String refString : references)<a name="line.130"></a>
<span class="sourceLineNo">131</span>            {<a name="line.131"></a>
<span class="sourceLineNo">132</span>                ThreadContainer ref = idTable.get(refString);<a name="line.132"></a>
<span class="sourceLineNo">133</span><a name="line.133"></a>
<span class="sourceLineNo">134</span>                // if this id doesnt have a container, create one<a name="line.134"></a>
<span class="sourceLineNo">135</span>                if (ref == null) {<a name="line.135"></a>
<span class="sourceLineNo">136</span>                    ref = new ThreadContainer();<a name="line.136"></a>
<span class="sourceLineNo">137</span>                    idTable.put(refString, ref);<a name="line.137"></a>
<span class="sourceLineNo">138</span>                }<a name="line.138"></a>
<span class="sourceLineNo">139</span><a name="line.139"></a>
<span class="sourceLineNo">140</span>                // Link references together in the order they appear in the References: header,<a name="line.140"></a>
<span class="sourceLineNo">141</span>                // IF they dont have a have a parent already &amp;&amp;<a name="line.141"></a>
<span class="sourceLineNo">142</span>                // IF it will not cause a circular reference<a name="line.142"></a>
<span class="sourceLineNo">143</span>                if ((parentRef != null)<a name="line.143"></a>
<span class="sourceLineNo">144</span>                    &amp;&amp; (ref.parent == null)<a name="line.144"></a>
<span class="sourceLineNo">145</span>                    &amp;&amp; (parentRef != ref)<a name="line.145"></a>
<span class="sourceLineNo">146</span>                    &amp;&amp; !(ref.findChild(parentRef))) {<a name="line.146"></a>
<span class="sourceLineNo">147</span>                    // Link ref into the parent's child list<a name="line.147"></a>
<span class="sourceLineNo">148</span>                    ref.parent = parentRef;<a name="line.148"></a>
<span class="sourceLineNo">149</span>                    ref.next = parentRef.child;<a name="line.149"></a>
<span class="sourceLineNo">150</span>                    parentRef.child = ref;<a name="line.150"></a>
<span class="sourceLineNo">151</span>                }<a name="line.151"></a>
<span class="sourceLineNo">152</span>                parentRef = ref;<a name="line.152"></a>
<span class="sourceLineNo">153</span>            }<a name="line.153"></a>
<span class="sourceLineNo">154</span>        }<a name="line.154"></a>
<span class="sourceLineNo">155</span><a name="line.155"></a>
<span class="sourceLineNo">156</span>        // parentRef is now set to the container of the last element in the references field. make that<a name="line.156"></a>
<span class="sourceLineNo">157</span>        // be the parent of this container, unless doing so causes a circular reference<a name="line.157"></a>
<span class="sourceLineNo">158</span>        if (parentRef != null<a name="line.158"></a>
<span class="sourceLineNo">159</span>            &amp;&amp; (parentRef == container || container.findChild(parentRef)))<a name="line.159"></a>
<span class="sourceLineNo">160</span>        {<a name="line.160"></a>
<span class="sourceLineNo">161</span>            parentRef = null;<a name="line.161"></a>
<span class="sourceLineNo">162</span>        }<a name="line.162"></a>
<span class="sourceLineNo">163</span><a name="line.163"></a>
<span class="sourceLineNo">164</span>        // if it has a parent already, its because we saw this message in a References: field, and presumed<a name="line.164"></a>
<span class="sourceLineNo">165</span>        // a parent based on the other entries in that field. Now that we have the actual message, we can<a name="line.165"></a>
<span class="sourceLineNo">166</span>        // throw away the old parent and use this new one<a name="line.166"></a>
<span class="sourceLineNo">167</span>        if (container.parent != null) {<a name="line.167"></a>
<span class="sourceLineNo">168</span>            ThreadContainer rest, prev;<a name="line.168"></a>
<span class="sourceLineNo">169</span><a name="line.169"></a>
<span class="sourceLineNo">170</span>            for (prev = null, rest = container.parent.child;<a name="line.170"></a>
<span class="sourceLineNo">171</span>                rest != null;<a name="line.171"></a>
<span class="sourceLineNo">172</span>                prev = rest, rest = rest.next) {<a name="line.172"></a>
<span class="sourceLineNo">173</span>                if (rest == container) {<a name="line.173"></a>
<span class="sourceLineNo">174</span>                    break;<a name="line.174"></a>
<span class="sourceLineNo">175</span>                }<a name="line.175"></a>
<span class="sourceLineNo">176</span>            }<a name="line.176"></a>
<span class="sourceLineNo">177</span><a name="line.177"></a>
<span class="sourceLineNo">178</span>            if (rest == null) {<a name="line.178"></a>
<span class="sourceLineNo">179</span>                throw new RuntimeException(<a name="line.179"></a>
<span class="sourceLineNo">180</span>                    "Didnt find "<a name="line.180"></a>
<span class="sourceLineNo">181</span>                        + container<a name="line.181"></a>
<span class="sourceLineNo">182</span>                        + " in parent"<a name="line.182"></a>
<span class="sourceLineNo">183</span>                        + container.parent);<a name="line.183"></a>
<span class="sourceLineNo">184</span>            }<a name="line.184"></a>
<span class="sourceLineNo">185</span><a name="line.185"></a>
<span class="sourceLineNo">186</span>            // Unlink this container from the parent's child list<a name="line.186"></a>
<span class="sourceLineNo">187</span>            if (prev == null) {<a name="line.187"></a>
<span class="sourceLineNo">188</span>                container.parent.child = container.next;<a name="line.188"></a>
<span class="sourceLineNo">189</span>            } else {<a name="line.189"></a>
<span class="sourceLineNo">190</span>                prev.next = container.next;<a name="line.190"></a>
<span class="sourceLineNo">191</span>            }<a name="line.191"></a>
<span class="sourceLineNo">192</span><a name="line.192"></a>
<span class="sourceLineNo">193</span>            container.next = null;<a name="line.193"></a>
<span class="sourceLineNo">194</span>            container.parent = null;<a name="line.194"></a>
<span class="sourceLineNo">195</span>        }<a name="line.195"></a>
<span class="sourceLineNo">196</span><a name="line.196"></a>
<span class="sourceLineNo">197</span>        // If we have a parent, link container into the parents child list<a name="line.197"></a>
<span class="sourceLineNo">198</span>        if (parentRef != null) {<a name="line.198"></a>
<span class="sourceLineNo">199</span>            container.parent = parentRef;<a name="line.199"></a>
<span class="sourceLineNo">200</span>            container.next = parentRef.child;<a name="line.200"></a>
<span class="sourceLineNo">201</span>            parentRef.child = container;<a name="line.201"></a>
<span class="sourceLineNo">202</span>        }<a name="line.202"></a>
<span class="sourceLineNo">203</span>    }<a name="line.203"></a>
<span class="sourceLineNo">204</span><a name="line.204"></a>
<span class="sourceLineNo">205</span>    /**<a name="line.205"></a>
<span class="sourceLineNo">206</span>     * Find the root set of all existing ThreadContainers<a name="line.206"></a>
<span class="sourceLineNo">207</span>     * @return root the ThreadContainer representing the root node<a name="line.207"></a>
<span class="sourceLineNo">208</span>     */<a name="line.208"></a>
<span class="sourceLineNo">209</span>    private ThreadContainer findRootSet() {<a name="line.209"></a>
<span class="sourceLineNo">210</span>        ThreadContainer root = new ThreadContainer();<a name="line.210"></a>
<span class="sourceLineNo">211</span>        Iterator&lt;String&gt; iter = idTable.keySet().iterator();<a name="line.211"></a>
<span class="sourceLineNo">212</span><a name="line.212"></a>
<span class="sourceLineNo">213</span>        while (iter.hasNext()) {<a name="line.213"></a>
<span class="sourceLineNo">214</span>            Object key = iter.next();<a name="line.214"></a>
<span class="sourceLineNo">215</span>            ThreadContainer c = idTable.get(key);<a name="line.215"></a>
<span class="sourceLineNo">216</span>            if (c.parent == null) {<a name="line.216"></a>
<span class="sourceLineNo">217</span>                if (c.next != null) {<a name="line.217"></a>
<span class="sourceLineNo">218</span>                    throw new RuntimeException(<a name="line.218"></a>
<span class="sourceLineNo">219</span>                            "c.next is " + c.next.toString());<a name="line.219"></a>
<span class="sourceLineNo">220</span>                }<a name="line.220"></a>
<span class="sourceLineNo">221</span>                c.next = root.child;<a name="line.221"></a>
<span class="sourceLineNo">222</span>                root.child = c;<a name="line.222"></a>
<span class="sourceLineNo">223</span>            }<a name="line.223"></a>
<span class="sourceLineNo">224</span>        }<a name="line.224"></a>
<span class="sourceLineNo">225</span>        return root;<a name="line.225"></a>
<span class="sourceLineNo">226</span>    }<a name="line.226"></a>
<span class="sourceLineNo">227</span><a name="line.227"></a>
<span class="sourceLineNo">228</span>    /**<a name="line.228"></a>
<span class="sourceLineNo">229</span>     * Delete any empty or dummy ThreadContainers<a name="line.229"></a>
<span class="sourceLineNo">230</span>     * @param parent<a name="line.230"></a>
<span class="sourceLineNo">231</span>     */<a name="line.231"></a>
<span class="sourceLineNo">232</span>    private void pruneEmptyContainers(ThreadContainer parent) {<a name="line.232"></a>
<span class="sourceLineNo">233</span>        ThreadContainer container, prev, next;<a name="line.233"></a>
<span class="sourceLineNo">234</span>        for (prev = null, container = parent.child, next = container.next;<a name="line.234"></a>
<span class="sourceLineNo">235</span>            container != null;<a name="line.235"></a>
<span class="sourceLineNo">236</span>            prev = container,<a name="line.236"></a>
<span class="sourceLineNo">237</span>                container = next,<a name="line.237"></a>
<span class="sourceLineNo">238</span>                next = (container == null ? null : container.next)) {<a name="line.238"></a>
<span class="sourceLineNo">239</span><a name="line.239"></a>
<span class="sourceLineNo">240</span>            // Is it empty and without any children? If so,delete it<a name="line.240"></a>
<span class="sourceLineNo">241</span>            if (container.threadable == null &amp;&amp; container.child == null) {<a name="line.241"></a>
<span class="sourceLineNo">242</span>                if (prev == null) {<a name="line.242"></a>
<span class="sourceLineNo">243</span>                    parent.child = container.next;<a name="line.243"></a>
<span class="sourceLineNo">244</span>                } else {<a name="line.244"></a>
<span class="sourceLineNo">245</span>                    prev.next = container.next;<a name="line.245"></a>
<span class="sourceLineNo">246</span>                }<a name="line.246"></a>
<span class="sourceLineNo">247</span><a name="line.247"></a>
<span class="sourceLineNo">248</span>                // Set container to prev so that prev keeps its same value the next time through the loop<a name="line.248"></a>
<span class="sourceLineNo">249</span>                container = prev;<a name="line.249"></a>
<span class="sourceLineNo">250</span>            }<a name="line.250"></a>
<span class="sourceLineNo">251</span><a name="line.251"></a>
<span class="sourceLineNo">252</span>            // Else if empty, with kids, and (not at root or only one kid)<a name="line.252"></a>
<span class="sourceLineNo">253</span>            else if (<a name="line.253"></a>
<span class="sourceLineNo">254</span>                container.threadable == null<a name="line.254"></a>
<span class="sourceLineNo">255</span>                    &amp;&amp; container.child != null<a name="line.255"></a>
<span class="sourceLineNo">256</span>                    &amp;&amp; (container.parent != null<a name="line.256"></a>
<span class="sourceLineNo">257</span>                        || container.child.next == null)) {<a name="line.257"></a>
<span class="sourceLineNo">258</span>                // We have an invalid/expired message with kids. Promote the kids to this level.<a name="line.258"></a>
<span class="sourceLineNo">259</span>                ThreadContainer tail;<a name="line.259"></a>
<span class="sourceLineNo">260</span>                ThreadContainer kids = container.child;<a name="line.260"></a>
<span class="sourceLineNo">261</span><a name="line.261"></a>
<span class="sourceLineNo">262</span>                // Remove this container and replace with 'kids'.<a name="line.262"></a>
<span class="sourceLineNo">263</span>                if (prev == null) {<a name="line.263"></a>
<span class="sourceLineNo">264</span>                    parent.child = kids;<a name="line.264"></a>
<span class="sourceLineNo">265</span>                } else {<a name="line.265"></a>
<span class="sourceLineNo">266</span>                    prev.next = kids;<a name="line.266"></a>
<span class="sourceLineNo">267</span>                }<a name="line.267"></a>
<span class="sourceLineNo">268</span><a name="line.268"></a>
<span class="sourceLineNo">269</span>                // Make each child's parent be this level's parent -&gt; i.e. promote the children. Make the last child's next point to this container's next<a name="line.269"></a>
<span class="sourceLineNo">270</span>                // i.e. splice kids into the list in place of container<a name="line.270"></a>
<span class="sourceLineNo">271</span>                for (tail = kids; tail.next != null; tail = tail.next) {<a name="line.271"></a>
<span class="sourceLineNo">272</span>                    tail.parent = container.parent;<a name="line.272"></a>
<span class="sourceLineNo">273</span>                }<a name="line.273"></a>
<span class="sourceLineNo">274</span><a name="line.274"></a>
<span class="sourceLineNo">275</span>                tail.parent = container.parent;<a name="line.275"></a>
<span class="sourceLineNo">276</span>                tail.next = container.next;<a name="line.276"></a>
<span class="sourceLineNo">277</span><a name="line.277"></a>
<span class="sourceLineNo">278</span>                // next currently points to the item after the inserted items in the chain - reset that so we process the newly<a name="line.278"></a>
<span class="sourceLineNo">279</span>                // promoted items next time round<a name="line.279"></a>
<span class="sourceLineNo">280</span>                next = kids;<a name="line.280"></a>
<span class="sourceLineNo">281</span><a name="line.281"></a>
<span class="sourceLineNo">282</span>                // Set container to prev so that prev keeps its same value the next time through the loop<a name="line.282"></a>
<span class="sourceLineNo">283</span>                container = prev;<a name="line.283"></a>
<span class="sourceLineNo">284</span>            } else if (container.child != null) {<a name="line.284"></a>
<span class="sourceLineNo">285</span>                // A real message , with kids<a name="line.285"></a>
<span class="sourceLineNo">286</span>                // Iterate over the children<a name="line.286"></a>
<span class="sourceLineNo">287</span>                pruneEmptyContainers(container);<a name="line.287"></a>
<span class="sourceLineNo">288</span>            }<a name="line.288"></a>
<span class="sourceLineNo">289</span>        }<a name="line.289"></a>
<span class="sourceLineNo">290</span>    }<a name="line.290"></a>
<span class="sourceLineNo">291</span><a name="line.291"></a>
<span class="sourceLineNo">292</span>    /**<a name="line.292"></a>
<span class="sourceLineNo">293</span>     *  If any two members of the root set have the same subject, merge them. This is to attempt to accomodate messages without References: headers.<a name="line.293"></a>
<span class="sourceLineNo">294</span>     */<a name="line.294"></a>
<span class="sourceLineNo">295</span>    private void gatherSubjects() {<a name="line.295"></a>
<span class="sourceLineNo">296</span><a name="line.296"></a>
<span class="sourceLineNo">297</span>        int count = 0;<a name="line.297"></a>
<span class="sourceLineNo">298</span><a name="line.298"></a>
<span class="sourceLineNo">299</span>        for (ThreadContainer c = root.child; c != null; c = c.next) {<a name="line.299"></a>
<span class="sourceLineNo">300</span>            count++;<a name="line.300"></a>
<span class="sourceLineNo">301</span>        }<a name="line.301"></a>
<span class="sourceLineNo">302</span><a name="line.302"></a>
<span class="sourceLineNo">303</span>        // TODO verify this will avoid rehashing<a name="line.303"></a>
<span class="sourceLineNo">304</span>        HashMap&lt;String, ThreadContainer&gt; subjectTable = new HashMap&lt;String, ThreadContainer&gt;((int) (count * 1.2), (float) 0.9);<a name="line.304"></a>
<span class="sourceLineNo">305</span>        count = 0;<a name="line.305"></a>
<span class="sourceLineNo">306</span><a name="line.306"></a>
<span class="sourceLineNo">307</span>        for (ThreadContainer c = root.child; c != null; c = c.next) {<a name="line.307"></a>
<span class="sourceLineNo">308</span>            Threadable threadable = c.threadable;<a name="line.308"></a>
<span class="sourceLineNo">309</span><a name="line.309"></a>
<span class="sourceLineNo">310</span>            // No threadable? If so, it is a dummy node in the root set.<a name="line.310"></a>
<span class="sourceLineNo">311</span>            // Only root set members may be dummies, and they alway have at least 2 kids<a name="line.311"></a>
<span class="sourceLineNo">312</span>            // Take the first kid as representative of the subject<a name="line.312"></a>
<span class="sourceLineNo">313</span>            if (threadable == null) {<a name="line.313"></a>
<span class="sourceLineNo">314</span>                threadable = c.child.threadable;<a name="line.314"></a>
<span class="sourceLineNo">315</span>            }<a name="line.315"></a>
<span class="sourceLineNo">316</span><a name="line.316"></a>
<span class="sourceLineNo">317</span>            String subj = threadable.simplifiedSubject();<a name="line.317"></a>
<span class="sourceLineNo">318</span><a name="line.318"></a>
<span class="sourceLineNo">319</span>            if (subj == null || subj.length() == 0) {<a name="line.319"></a>
<span class="sourceLineNo">320</span>                continue;<a name="line.320"></a>
<span class="sourceLineNo">321</span>            }<a name="line.321"></a>
<span class="sourceLineNo">322</span><a name="line.322"></a>
<span class="sourceLineNo">323</span>            ThreadContainer old = subjectTable.get(subj);<a name="line.323"></a>
<span class="sourceLineNo">324</span><a name="line.324"></a>
<span class="sourceLineNo">325</span>            // Add this container to the table iff:<a name="line.325"></a>
<span class="sourceLineNo">326</span>            // - There exists no container with this subject<a name="line.326"></a>
<span class="sourceLineNo">327</span>            // - or this is a dummy container and the old one is not - the dummy one is<a name="line.327"></a>
<span class="sourceLineNo">328</span>            // more interesting as a root, so put it in the table instead<a name="line.328"></a>
<span class="sourceLineNo">329</span>            // - The container in the table has a "Re:" version of this subject, and<a name="line.329"></a>
<span class="sourceLineNo">330</span>            // this container has a non-"Re:" version of this subject. The non-"Re:" version<a name="line.330"></a>
<span class="sourceLineNo">331</span>            // is the more interesting of the two.<a name="line.331"></a>
<span class="sourceLineNo">332</span>            if (old == null<a name="line.332"></a>
<span class="sourceLineNo">333</span>                || (c.threadable == null &amp;&amp; old.threadable != null)<a name="line.333"></a>
<span class="sourceLineNo">334</span>                || (old.threadable != null<a name="line.334"></a>
<span class="sourceLineNo">335</span>                    &amp;&amp; old.threadable.subjectIsReply()<a name="line.335"></a>
<span class="sourceLineNo">336</span>                    &amp;&amp; c.threadable != null<a name="line.336"></a>
<span class="sourceLineNo">337</span>                    &amp;&amp; !c.threadable.subjectIsReply())) {<a name="line.337"></a>
<span class="sourceLineNo">338</span>                subjectTable.put(subj, c);<a name="line.338"></a>
<span class="sourceLineNo">339</span>                count++;<a name="line.339"></a>
<span class="sourceLineNo">340</span>            }<a name="line.340"></a>
<span class="sourceLineNo">341</span>        }<a name="line.341"></a>
<span class="sourceLineNo">342</span><a name="line.342"></a>
<span class="sourceLineNo">343</span>        // If the table is empty, we're done<a name="line.343"></a>
<span class="sourceLineNo">344</span>        if (count == 0) {<a name="line.344"></a>
<span class="sourceLineNo">345</span>            return;<a name="line.345"></a>
<span class="sourceLineNo">346</span>        }<a name="line.346"></a>
<span class="sourceLineNo">347</span><a name="line.347"></a>
<span class="sourceLineNo">348</span>        // subjectTable is now populated with one entry for each subject which occurs in the<a name="line.348"></a>
<span class="sourceLineNo">349</span>        // root set. Iterate over the root set, and gather together the difference.<a name="line.349"></a>
<span class="sourceLineNo">350</span>        ThreadContainer prev, c, rest;<a name="line.350"></a>
<span class="sourceLineNo">351</span>        for (prev = null, c = root.child, rest = c.next;<a name="line.351"></a>
<span class="sourceLineNo">352</span>            c != null;<a name="line.352"></a>
<span class="sourceLineNo">353</span>            prev = c, c = rest, rest = (rest == null ? null : rest.next)) {<a name="line.353"></a>
<span class="sourceLineNo">354</span>            Threadable threadable = c.threadable;<a name="line.354"></a>
<span class="sourceLineNo">355</span><a name="line.355"></a>
<span class="sourceLineNo">356</span>            // is it a dummy node?<a name="line.356"></a>
<span class="sourceLineNo">357</span>            if (threadable == null) {<a name="line.357"></a>
<span class="sourceLineNo">358</span>                threadable = c.child.threadable;<a name="line.358"></a>
<span class="sourceLineNo">359</span>            }<a name="line.359"></a>
<span class="sourceLineNo">360</span><a name="line.360"></a>
<span class="sourceLineNo">361</span>            String subj = threadable.simplifiedSubject();<a name="line.361"></a>
<span class="sourceLineNo">362</span><a name="line.362"></a>
<span class="sourceLineNo">363</span>            // Dont thread together all subjectless messages<a name="line.363"></a>
<span class="sourceLineNo">364</span>            if (subj == null || subj.length() == 0) {<a name="line.364"></a>
<span class="sourceLineNo">365</span>                continue;<a name="line.365"></a>
<span class="sourceLineNo">366</span>            }<a name="line.366"></a>
<span class="sourceLineNo">367</span><a name="line.367"></a>
<span class="sourceLineNo">368</span>            ThreadContainer old = subjectTable.get(subj);<a name="line.368"></a>
<span class="sourceLineNo">369</span><a name="line.369"></a>
<span class="sourceLineNo">370</span>            if (old == c) { // That's us<a name="line.370"></a>
<span class="sourceLineNo">371</span>                continue;<a name="line.371"></a>
<span class="sourceLineNo">372</span>            }<a name="line.372"></a>
<span class="sourceLineNo">373</span><a name="line.373"></a>
<span class="sourceLineNo">374</span>            // We have now found another container in the root set with the same subject<a name="line.374"></a>
<span class="sourceLineNo">375</span>            // Remove the "second" message from the root set<a name="line.375"></a>
<span class="sourceLineNo">376</span>            if (prev == null) {<a name="line.376"></a>
<span class="sourceLineNo">377</span>                root.child = c.next;<a name="line.377"></a>
<span class="sourceLineNo">378</span>            } else {<a name="line.378"></a>
<span class="sourceLineNo">379</span>                prev.next = c.next;<a name="line.379"></a>
<span class="sourceLineNo">380</span>            }<a name="line.380"></a>
<span class="sourceLineNo">381</span>            c.next = null;<a name="line.381"></a>
<span class="sourceLineNo">382</span><a name="line.382"></a>
<span class="sourceLineNo">383</span>            if (old.threadable == null &amp;&amp; c.threadable == null) {<a name="line.383"></a>
<span class="sourceLineNo">384</span>                // both dummies - merge them<a name="line.384"></a>
<span class="sourceLineNo">385</span>                ThreadContainer tail;<a name="line.385"></a>
<span class="sourceLineNo">386</span>                for (tail = old.child;<a name="line.386"></a>
<span class="sourceLineNo">387</span>                    tail != null &amp;&amp; tail.next != null;<a name="line.387"></a>
<span class="sourceLineNo">388</span>                    tail = tail.next) {<a name="line.388"></a>
<span class="sourceLineNo">389</span>                    // do nothing<a name="line.389"></a>
<span class="sourceLineNo">390</span>                }<a name="line.390"></a>
<span class="sourceLineNo">391</span><a name="line.391"></a>
<span class="sourceLineNo">392</span>                if (tail != null) { // protect against possible NPE<a name="line.392"></a>
<span class="sourceLineNo">393</span>                    tail.next = c.child;<a name="line.393"></a>
<span class="sourceLineNo">394</span>                }<a name="line.394"></a>
<span class="sourceLineNo">395</span><a name="line.395"></a>
<span class="sourceLineNo">396</span>                for (tail = c.child; tail != null; tail = tail.next) {<a name="line.396"></a>
<span class="sourceLineNo">397</span>                    tail.parent = old;<a name="line.397"></a>
<span class="sourceLineNo">398</span>                }<a name="line.398"></a>
<span class="sourceLineNo">399</span><a name="line.399"></a>
<span class="sourceLineNo">400</span>                c.child = null;<a name="line.400"></a>
<span class="sourceLineNo">401</span>            } else if (<a name="line.401"></a>
<span class="sourceLineNo">402</span>                old.threadable == null<a name="line.402"></a>
<span class="sourceLineNo">403</span>                    || (c.threadable != null<a name="line.403"></a>
<span class="sourceLineNo">404</span>                        &amp;&amp; c.threadable.subjectIsReply()<a name="line.404"></a>
<span class="sourceLineNo">405</span>                        &amp;&amp; !old.threadable.subjectIsReply())) {<a name="line.405"></a>
<span class="sourceLineNo">406</span>                // Else if old is empty, or c has "Re:" and old does not  ==&gt; make this message a child of old<a name="line.406"></a>
<span class="sourceLineNo">407</span>                c.parent = old;<a name="line.407"></a>
<span class="sourceLineNo">408</span>                c.next = old.child;<a name="line.408"></a>
<span class="sourceLineNo">409</span>                old.child = c;<a name="line.409"></a>
<span class="sourceLineNo">410</span>            } else {<a name="line.410"></a>
<span class="sourceLineNo">411</span>                // else make the old and new messages be children of a new dummy container.<a name="line.411"></a>
<span class="sourceLineNo">412</span>                // We create a new container object for old.msg and empty the old container<a name="line.412"></a>
<span class="sourceLineNo">413</span>                ThreadContainer newc = new ThreadContainer();<a name="line.413"></a>
<span class="sourceLineNo">414</span>                newc.threadable = old.threadable;<a name="line.414"></a>
<span class="sourceLineNo">415</span>                newc.child = old.child;<a name="line.415"></a>
<span class="sourceLineNo">416</span><a name="line.416"></a>
<span class="sourceLineNo">417</span>                for (ThreadContainer tail = newc.child;<a name="line.417"></a>
<span class="sourceLineNo">418</span>                    tail != null;<a name="line.418"></a>
<span class="sourceLineNo">419</span>                    tail = tail.next)<a name="line.419"></a>
<span class="sourceLineNo">420</span>                {<a name="line.420"></a>
<span class="sourceLineNo">421</span>                    tail.parent = newc;<a name="line.421"></a>
<span class="sourceLineNo">422</span>                }<a name="line.422"></a>
<span class="sourceLineNo">423</span><a name="line.423"></a>
<span class="sourceLineNo">424</span>                old.threadable = null;<a name="line.424"></a>
<span class="sourceLineNo">425</span>                old.child = null;<a name="line.425"></a>
<span class="sourceLineNo">426</span><a name="line.426"></a>
<span class="sourceLineNo">427</span>                c.parent = old;<a name="line.427"></a>
<span class="sourceLineNo">428</span>                newc.parent = old;<a name="line.428"></a>
<span class="sourceLineNo">429</span><a name="line.429"></a>
<span class="sourceLineNo">430</span>                // Old is now a dummy- give it 2 kids , c and newc<a name="line.430"></a>
<span class="sourceLineNo">431</span>                old.child = c;<a name="line.431"></a>
<span class="sourceLineNo">432</span>                c.next = newc;<a name="line.432"></a>
<span class="sourceLineNo">433</span>            }<a name="line.433"></a>
<span class="sourceLineNo">434</span>            // We've done a merge, so keep the same prev<a name="line.434"></a>
<span class="sourceLineNo">435</span>            c = prev;<a name="line.435"></a>
<span class="sourceLineNo">436</span>        }<a name="line.436"></a>
<span class="sourceLineNo">437</span><a name="line.437"></a>
<span class="sourceLineNo">438</span>        subjectTable.clear();<a name="line.438"></a>
<span class="sourceLineNo">439</span>        subjectTable = null;<a name="line.439"></a>
<span class="sourceLineNo">440</span><a name="line.440"></a>
<span class="sourceLineNo">441</span>    }<a name="line.441"></a>
<span class="sourceLineNo">442</span><a name="line.442"></a>
<span class="sourceLineNo">443</span><a name="line.443"></a>
<span class="sourceLineNo">444</span>    // DEPRECATED METHODS - for API compatibility only - DO NOT USE<a name="line.444"></a>
<span class="sourceLineNo">445</span><a name="line.445"></a>
<span class="sourceLineNo">446</span>    /**<a name="line.446"></a>
<span class="sourceLineNo">447</span>     * The client passes in an array of Threadable objects, and<a name="line.447"></a>
<span class="sourceLineNo">448</span>     * the Threader constructs a connected 'graph' of messages<a name="line.448"></a>
<span class="sourceLineNo">449</span>     * @param messages array of messages to thread<a name="line.449"></a>
<span class="sourceLineNo">450</span>     * @return null if messages == null or root.child == null<a name="line.450"></a>
<span class="sourceLineNo">451</span>     * @deprecated (2.2) prefer {@link #thread(List)}<a name="line.451"></a>
<span class="sourceLineNo">452</span>     */<a name="line.452"></a>
<span class="sourceLineNo">453</span>    @Deprecated<a name="line.453"></a>
<span class="sourceLineNo">454</span>    public Threadable thread(Threadable[] messages) {<a name="line.454"></a>
<span class="sourceLineNo">455</span>        return thread(java.util.Arrays.asList(messages));<a name="line.455"></a>
<span class="sourceLineNo">456</span>    }<a name="line.456"></a>
<span class="sourceLineNo">457</span><a name="line.457"></a>
<span class="sourceLineNo">458</span>}<a name="line.458"></a>




























































</pre>
</div>
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